1. Field of the Invention
The present invention generally relates to machine tools, and particularly to a desktop milling machine with an ovate-shaped bridge.
2. Description of the Related Art
Micro-scale (and meso-scale) components have generally been produced by conventional machine tools. Since by definition micro components are small, the dimensional tolerance allowances would also be small, thereby creating a high incidence of error when utilizing conventional machine tools to manufacture the micro components. To alleviate these errors, relatively small computer numerical control (CNC) desktop milling machines have been employed to manufacture micro components. The use of these desktop milling machines has greatly reduced manufacturing errors in the production of micro components, saving both time and money. However, the high speed manufacturing techniques performed by the desktop machine produce high-frequency induced loads and temperature rises that can cause distorting resonances in the frame or bridge of the machine.
The major problem that may result from the resonances is that the disturbance set up in the bridge is also easily transferable through relatively weak joints back onto the spindle and tool assembly, which are supported on the bridge, causing deformations. Although such deformations might be slight, they have a high impact on the accuracy of a micro-milling procedure. The effect of this on the already complex dynamics of the spindle-tool system may be enough to cause bad surface quality, chatter, and tool breakage.
Hence, it is important that the bridge has higher natural frequencies and stiffness to resist these deformation resonances. A design that would produce a bridge that has a higher natural frequency than the related art bridges would alleviate the effect of the distorting resonances and would greatly enhance the efficiency of the desktop milling process. Thus, a desktop milling machine with an ovate-shaped bridge solving the aforementioned problems is desired.